1. Field of the Invention
This invention relates to a valve-coupling assembly having a manifold electromagnetic valve for controlling supply of compressed air to pneumatic equipments and couplings for connecting tubes which respectively connect the manifold electromagnetic valve to the pneumatic equipments and guide the compressed air.
2. Related Art Statement
A manifold electromagnetic valve is an electromagnetic valve of a type, in which, normally, a plurality of electromagnetic valves are mounted on a manifold block formed therein with an air supply port and air exhaust ports and supply of air pressure to the respective electromagnetic valves and exhaust of air pressure therefrom can be performed commonly through the air supply port and the air exhaust ports formed in the manifold block. And, there has been developed such a manifold electromagnetic valve too wherein only an air supply port is formed in a manifold block and exhaust from respective electromagnetic valves is directly carried out from the respective electromagnetic valves. concentrically control a plurality of pneumatic equipments, for example, actuators such as air cylinders, so that a number of manifold electromagnetic valves are used in fields where a multiplicity of pneumatic equipments such as actuators are used as in an assembly line for parts or products.
As for connection between a plurality of electromagnetic valves mounted on the manifold block and pneumatic actuators such as air cylinders through the tubes for guiding air, there are two types of piping systems, i.e., a manifold piping system wherein the connection is made at the manifold block, and a valve piping system wherein the connection is made at the respective electromagnetic valves. The valve piping system has the advantage that the electromagnetic valves can be replaced together with the actuators, and the manifold piping system has the advantage that the electromagnetic valves can be exchanged without removing the tubes.
Selection of a piping system is determined depending on a place where the manifold electromagnetic valve is used. However, once either is selected, the selected system cannot be easily changed over to the other afterward. If a requirement of a piping system to be used is changed over to the other type, it is necessary to change the manifold electromagnetic valve over to the other type.
The manifold electromagnetic valve is connected to an actuator by use of a tube, and the tube is connected to the manifold electromagnetic valve through a pipe coupling. When the tube is connected to an output port of the manifold electromagnetic valve, the inner diameter of the tube is set so as to be suitable to the air flow rate through the tube.
Only tubes of one and same inner diameter size can be selected to be coupled to a normal pipe coupling and it has heretofore been impossible to interchangeably connect two kinds of tubes having different diameters from each other to a pipe coupling. However, in process of using a manifold electromagnetic valve, there may arise necessity for changing responsiveness of a pneumatic equipment, i.e., an operating speed of the equipment. In that case, the tube should be changed over to one different in inner diameter.
In this case, because only a tube having a particular diameter can be coupled to a conventional pipe coupling, so that, in order to connect a tube of a different diameter, the pipe coupling should be changed over to one having the size corresponding to the diameter of a new tube after the change, thereby making tube-exchanging work troublesome. Furthermore, it is necessary to prepare a plurality of pipe couplings in accordance with different tube diameters, thus making management of pipe couplings complicated.